I first just asked for a solution similar to Debian dummy packages and get tons  of insults.
Then I explained why I (and I know a lot of other people) will install e.g. GNOME. I'll do it again. We might wish to use this DE or simply GDM as login manager. I don't blame Arch Linux packages, I just blame answers like "don't use gnome".
I was silent since days, stopped putting in my 2 cents all the time and now I asked for help and get those answers?! That's strange and creepy.
Anyway, if somebody should know a solution how to use GNOME without PA, any hints are welcome.
 OT, but too funny, since I got all mails two times, even more than 1k of old mails Evolution already had downloaded from the server.